pwc-dec23.c

webcam device driver

 *   . G . G . G . G . G . G . G
 *   . . . . . . . . . . . . . .
 *   . G . G . G . G . G . G . G
 *   . . . . . . . . . . . . . .
 *   or
 *   . . . . . . . . . . . . . .
 *   G . G . G . G . G . G . G .
 *   . . . . . . . . . . . . . .
 *   G . G . G . G . G . G . G .
*/
static void copy_image_block_Green(const int *src, unsigned char *dst, unsigned int bytes_per_line, unsigned int scalebits)
{
#if UNROLL_LOOP_FOR_COPY
	/* Unroll all loops */
	const unsigned char *cm = pwc_crop_table+MAX_OUTER_CROP_VALUE;
	unsigned char *d = dst;
	const int *c = src;

	d[0] = cm[c[0] >> scalebits];
	d[2] = cm[c[1] >> scalebits];
	d[4] = cm[c[2] >> scalebits];
	d[6] = cm[c[3] >> scalebits];
	d[8] = cm[c[4] >> scalebits];
	d[10] = cm[c[5] >> scalebits];
	d[12] = cm[c[6] >> scalebits];
	d[14] = cm[c[7] >> scalebits];

	d = dst + bytes_per_line;
	d[0] = cm[c[8] >> scalebits];
	d[2] = cm[c[9] >> scalebits];
	d[4] = cm[c[10] >> scalebits];
	d[6] = cm[c[11] >> scalebits];
	d[8] = cm[c[12] >> scalebits];
	d[10] = cm[c[13] >> scalebits];
	d[12] = cm[c[14] >> scalebits];
	d[14] = cm[c[15] >> scalebits];
#else
	int i;
	unsigned char *d;
	const int *c = src;

	d = dst;
	for (i = 0; i < 8; i++, c++)
		d[i*2] = CLAMP((*c) >> scalebits);

	d = dst + bytes_per_line;
	for (i = 0; i < 8; i++, c++)
		d[i*2] = CLAMP((*c) >> scalebits);
#endif
}
#endif

#if ENABLE_BAYER_DECODER
/*
 * Format: 4x4 pixels
 *   R . R . R . R
 *   . B . B . B .
 *   R . R . R . R
 *   . B . B . B .
 */
static void copy_image_block_RedBlue(const int *src, unsigned char *dst, unsigned int bytes_per_line, unsigned int scalebits)
{
#if UNROLL_LOOP_FOR_COPY
	/* Unroll all loops */
	const unsigned char *cm = pwc_crop_table+MAX_OUTER_CROP_VALUE;
	unsigned char *d = dst;
	const int *c = src;

	d[0] = cm[c[0] >> scalebits];
	d[2] = cm[c[1] >> scalebits];
	d[4] = cm[c[2] >> scalebits];
	d[6] = cm[c[3] >> scalebits];

	d = dst + bytes_per_line;
	d[1] = cm[c[4] >> scalebits];
	d[3] = cm[c[5] >> scalebits];
	d[5] = cm[c[6] >> scalebits];
	d[7] = cm[c[7] >> scalebits];

	d = dst + bytes_per_line*2;
	d[0] = cm[c[8] >> scalebits];
	d[2] = cm[c[9] >> scalebits];
	d[4] = cm[c[10] >> scalebits];
	d[6] = cm[c[11] >> scalebits];

	d = dst + bytes_per_line*3;
	d[1] = cm[c[12] >> scalebits];
	d[3] = cm[c[13] >> scalebits];
	d[5] = cm[c[14] >> scalebits];
	d[7] = cm[c[15] >> scalebits];
#else
	int i;
	unsigned char *d;
	const int *c = src;

	d = dst;
	for (i = 0; i < 4; i++, c++)
		d[i*2] = CLAMP((*c) >> scalebits);

	d = dst + bytes_per_line;
	for (i = 0; i < 4; i++, c++)
		d[i*2+1] = CLAMP((*c) >> scalebits);

	d = dst + bytes_per_line*2;
	for (i = 0; i < 4; i++, c++)
		d[i*2] = CLAMP((*c) >> scalebits);

	d = dst + bytes_per_line*3;
	for (i = 0; i < 4; i++, c++)
		d[i*2+1] = CLAMP((*c) >> scalebits);
#endif
}
#endif

/*
 * To manage the stream, we keep bits in a 32 bits register.
 * fill_nbits(n): fill the reservoir with at least n bits
 * skip_bits(n): discard n bits from the reservoir
 * get_bits(n): fill the reservoir, returns the first n bits and discard the
 *              bits from the reservoir.
 * __get_nbits(n): faster version of get_bits(n), but asumes that the reservoir
 *                 contains at least n bits. bits returned is discarded.
 */
#define fill_nbits(pdec, nbits_wanted) do { \
   while (pdec->nbits_in_reservoir<(nbits_wanted)) \
    { \
      pdec->reservoir |= (*(pdec->stream)++) << (pdec->nbits_in_reservoir); \
      pdec->nbits_in_reservoir += 8; \
    } \
}  while(0);

#define skip_nbits(pdec, nbits_to_skip) do { \
   pdec->reservoir >>= (nbits_to_skip); \
   pdec->nbits_in_reservoir -= (nbits_to_skip); \
}  while(0);

#define get_nbits(pdec, nbits_wanted, result) do { \
   fill_nbits(pdec, nbits_wanted); \
   result = (pdec->reservoir) & ((1U<<(nbits_wanted))-1); \
   skip_nbits(pdec, nbits_wanted); \
}  while(0);

#define __get_nbits(pdec, nbits_wanted, result) do { \
   result = (pdec->reservoir) & ((1U<<(nbits_wanted))-1); \
   skip_nbits(pdec, nbits_wanted); \
}  while(0);

#define look_nbits(pdec, nbits_wanted) \
   ((pdec->reservoir) & ((1U<<(nbits_wanted))-1))

/*
 * Decode a 4x4 pixel block
 */
static void decode_block(struct pwc_dec23_private *pdec,
			 const unsigned char *ptable0004,
			 const unsigned char *ptable8004)
{
	unsigned int primary_color;
	unsigned int channel_v, offset1, op;
	int i;

	fill_nbits(pdec, 16);
	__get_nbits(pdec, pdec->nbits, primary_color);

	if (look_nbits(pdec,2) == 0) {
		skip_nbits(pdec, 2);
		/* Very simple, the color is the same for all pixels of the square */
		for (i = 0; i < 16; i++)
			pdec->temp_colors[i] = pdec->table_dc00[primary_color];

		return;
	}

	/* This block is encoded with small pattern */
	for (i = 0; i < 16; i++)
		pdec->temp_colors[i] = pdec->table_d800[primary_color];

	__get_nbits(pdec, 3, channel_v);
	channel_v = ((channel_v & 1) << 2) | (channel_v & 2) | ((channel_v & 4) >> 2);

	ptable0004 += (channel_v * 128);
	ptable8004 += (channel_v * 32);

	offset1 = 0;
	do
	{
		unsigned int htable_idx, rows = 0;
		const unsigned int *block;

		/* [  zzzz y x x ]
		 *     xx == 00 :=> end of the block def, remove the two bits from the stream
		 *    yxx == 111
		 *    yxx == any other value
		 *    
		 */
		fill_nbits(pdec, 16);
		htable_idx = look_nbits(pdec, 6);
		op = hash_table_ops[htable_idx * 4];

		if (op == 2) {
			skip_nbits(pdec, 2);

		} else if (op == 1) {
			/* 15bits [ xxxx xxxx yyyy 111 ]
			 * yyy => offset in the table8004
			 * xxx => offset in the tabled004 (tree)
			 */
			unsigned int mask, shift;
			unsigned int nbits, col1;
			unsigned int yyyy;

			skip_nbits(pdec, 3);
			/* offset1 += yyyy */
			__get_nbits(pdec, 4, yyyy);
			offset1 += 1 + yyyy;
			offset1 &= 0x0F;
			nbits = ptable8004[offset1 * 2];

			/* col1 = xxxx xxxx */
			__get_nbits(pdec, nbits+1, col1);

			/* Bit mask table */
			mask = pdec->table_bitpowermask[nbits][col1];
			shift = ptable8004[offset1 * 2 + 1];
			rows = ((mask << shift) + 0x80) & 0xFF;

			block = pdec->table_subblock[rows];
			for (i = 0; i < 16; i++)
				pdec->temp_colors[i] += block[MulIdx[offset1][i]];

		} else {
			/* op == 0
			 * offset1 is coded on 3 bits
			 */    
			unsigned int shift;

			offset1 += hash_table_ops [htable_idx * 4 + 2];
			offset1 &= 0x0F;

			rows = ptable0004[offset1 + hash_table_ops [htable_idx * 4 + 3]];
			block = pdec->table_subblock[rows];
			for (i = 0; i < 16; i++)
				pdec->temp_colors[i] += block[MulIdx[offset1][i]];

			shift = hash_table_ops[htable_idx * 4 + 1];
			skip_nbits(pdec, shift);
		}

	} while (op != 2);

}

static void DecompressBand23(struct pwc_dec23_private *pdec,
			     const unsigned char *rawyuv,
			     unsigned char *planar_y,
			     unsigned char *planar_u,
			     unsigned char *planar_v,
			     unsigned int   compressed_image_width,
			     unsigned int   real_image_width)
{
	int compression_index, nblocks;
	const unsigned char *ptable0004;
	const unsigned char *ptable8004;

	pdec->reservoir = 0;
	pdec->nbits_in_reservoir = 0;
	pdec->stream = rawyuv + 1;	/* The first byte of the stream is skipped */

	get_nbits(pdec, 4, compression_index);

	/* pass 1: uncompress Y component */
	nblocks = compressed_image_width / 4;

	ptable0004 = pdec->table_0004_pass1[compression_index];
	ptable8004 = pdec->table_8004_pass1[compression_index];

	/* Each block decode a square of 4x4 */
	while (nblocks) {
		decode_block(pdec, ptable0004, ptable8004);
		copy_image_block_Y(pdec->temp_colors, planar_y, real_image_width, pdec->scalebits);
		planar_y += 4;
		nblocks--;
	}

	/* pass 2: uncompress UV component */
	nblocks = compressed_image_width / 8;

	ptable0004 = pdec->table_0004_pass2[compression_index];
	ptable8004 = pdec->table_8004_pass2[compression_index];

	/* Each block decode a square of 4x4 */
	while (nblocks) {
		decode_block(pdec, ptable0004, ptable8004);
		copy_image_block_CrCb(pdec->temp_colors, planar_u, real_image_width/2, pdec->scalebits);

		decode_block(pdec, ptable0004, ptable8004);
		copy_image_block_CrCb(pdec->temp_colors, planar_v, real_image_width/2, pdec->scalebits);

		planar_v += 8;
		planar_u += 8;
		nblocks -= 2;
	}

}

#if ENABLE_BAYER_DECODER
/*
 * Size need to be a multiple of 8 in width
 *
 * Return a block of four line encoded like this:
 *
 *   G R G R G R G R G R G R G R G R
 *   B G B G B G B G B G B G B G B G
 *   G R G R G R G R G R G R G R G R
 *   B G B G B G B G B G B G B G B G
 * 
 */
static void DecompressBandBayer(struct pwc_dec23_private *pdec,
    				const unsigned char *rawyuv,
				unsigned char *rgbbayer,
				unsigned int   compressed_image_width,
				unsigned int   real_image_width)
{
	int compression_index, nblocks;
	const unsigned char *ptable0004;
	const unsigned char *ptable8004;
	unsigned char *dest;

	pdec->reservoir = 0;
	pdec->nbits_in_reservoir = 0;
	pdec->stream = rawyuv + 1;	/* The first byte of the stream is skipped */

	get_nbits(pdec, 4, compression_index);

	/* pass 1: uncompress RB component */
	nblocks = compressed_image_width / 4;

	ptable0004 = pdec->table_0004_pass1[compression_index];
	ptable8004 = pdec->table_8004_pass1[compression_index];
	dest = rgbbayer;

	/* Each block decode a square of 4x4 */
	while (nblocks) {
		decode_block(pdec, ptable0004, ptable8004);
		copy_image_block_RedBlue(pdec->temp_colors, rgbbayer, real_image_width, pdec->scalebits);
		dest += 8;
		nblocks--;
	}

	/* pass 2: uncompress G component */
	nblocks = compressed_image_width / 8;

	ptable0004 = pdec->table_0004_pass2[compression_index];
	ptable8004 = pdec->table_8004_pass2[compression_index];

	/* Each block decode a square of 4x4 */
	while (nblocks) {
		decode_block(pdec, ptable0004, ptable8004);
		copy_image_block_Green(pdec->temp_colors, rgbbayer+1, real_image_width, pdec->scalebits);

		decode_block(pdec, ptable0004, ptable8004);
		copy_image_block_Green(pdec->temp_colors, rgbbayer+real_image_width, real_image_width, pdec->scalebits);

		rgbbayer += 16;
		nblocks -= 2;
	}
}
#endif


/**
 *
 * Uncompress a pwc23 buffer.
 *
 * pwc.view: size of the image wanted
 * pwc.image: size of the image returned by the camera
 * pwc.offset: (x,y) to displayer image in the view
 *
 * src: raw data
 * dst: image output
 * flags: PWCX_FLAG_PLANAR or PWCX_FLAG_BAYER
 */
void pwc_dec23_decompress(const struct pwc_device *pwc,
			  const void *src,
			  void *dst,
			  int flags)
{
	int bandlines_left, stride, bytes_per_block;

	bandlines_left = pwc->image.y / 4;
	bytes_per_block = pwc->view.x * 4;

	if (flags & PWCX_FLAG_BAYER) {
#if ENABLE_BAYER_DECODER
		/* RGB Bayer format */
		unsigned char *rgbout;

		stride = pwc->view.x * pwc->offset.y;
		rgbout = dst + stride + pwc->offset.x;


		while (bandlines_left--) {

			DecompressBandBayer(pwc->decompress_data,
					    src,
					    rgbout,
					    pwc->image.x, pwc->view.x);

			src += pwc->vbandlength;
			rgbout += bytes_per_block;

		}	
#else
		memcpy(dst, 0, pwc->view.x * pwc->view.y);
#endif

	} else {
		/* YUV420P image format */
		unsigned char *pout_planar_y;
		unsigned char *pout_planar_u;
		unsigned char *pout_planar_v;
		unsigned int   plane_size;

		plane_size = pwc->view.x * pwc->view.y;

		/* offset in Y plane */
		stride = pwc->view.x * pwc->offset.y;
		pout_planar_y = dst + stride + pwc->offset.x;

		/* offsets in U/V planes */
		stride = (pwc->view.x * pwc->offset.y) / 4 + pwc->offset.x / 2;
		pout_planar_u = dst + plane_size + stride;
		pout_planar_v = dst + plane_size + plane_size / 4 + stride;

		while (bandlines_left--) {

			DecompressBand23(pwc->decompress_data,
				         src,
					 pout_planar_y, pout_planar_u, pout_planar_v,
					 pwc->image.x, pwc->view.x);
			src += pwc->vbandlength;
			pout_planar_y += bytes_per_block;
			pout_planar_u += pwc->view.x;
			pout_planar_v += pwc->view.x;

		}	

	}

}

void pwc_dec23_exit(void)
{
	/* Do nothing */

}

/**
 * Allocate a private structure used by lookup table.
 * You must call kfree() to free the memory allocated.
 */
int pwc_dec23_alloc(struct pwc_device *pwc)
{
	pwc->decompress_data = kmalloc(sizeof(struct pwc_dec23_private), GFP_KERNEL);
	if (pwc->decompress_data == NULL)
		return -ENOMEM;
	return 0;
}

/* vim: set cino= formatoptions=croql cindent shiftwidth=8 tabstop=8: */